Manatee

How to anonymize a screenshot or photo before posting it

· 7 min read

Anonymizing an image is two separate jobs. The first is the visible content: names, faces, the clock in the menu bar, a window reflection. The second is the invisible content: GPS coordinates, the camera model, and the timestamp stored in the file. Preview handles both for a single image (Markup for redaction, the Inspector for location), and Manatee’s Clean mode handles the metadata half for a batch. Do the visible half first, the metadata half last, and check the final file before posting.

Two kinds of leak

A screenshot taken on a Mac has no GPS and no camera model. It does have a creation timestamp in the file, and its default filename (Screenshot 2026-08-23 at 10.14.52.png) states the date and time to the second. Its real exposure is what is on the screen: your name in the menu bar or an app’s account menu, the Wi-Fi network name, notification banners, browser tabs and bookmarks, the Dock, the clock, and whatever document is behind the window you meant to share.

A photo from a phone or camera is the reverse. The visible content is usually what you intended, but the file carries coordinates, the device model, the capture time, and often a software version. A screenshot of a photo on an iPhone carries none of that, which is why people sometimes screenshot their own photos before posting; it works, at the cost of resolution.

Both kinds need a pass, and the order matters: redact first, then strip metadata from the redacted output. Doing it the other way around means your editing app may write fresh metadata into the final file.

Redact the visible content with Preview

Preview’s Markup tools are enough for most images, with one rule: cover, never smudge.

  1. Open the image in Preview and click the Markup toolbar button (the pen tip in a circle), or choose View > Show Markup Toolbar.
  2. Choose the Shapes tool and pick the rectangle.
  3. Draw a rectangle over the area to hide. In the Fill Color control choose solid black (or any opaque color) and set the Border Color to the same, so there is no outline.
  4. Repeat for every name, face, address, and account detail.
  5. For PDFs, Preview in macOS Ventura and later has a dedicated Redact tool in the Markup toolbar that permanently removes the content beneath it, which is the better choice for documents.
  6. Choose File > Export, pick PNG or JPEG, and save under a new name. Exporting flattens the shapes into the pixels. Do not simply Save, which for some formats can keep the markup as removable annotations.

Two things that do not work. The highlighter and pen tools draw semi-transparent strokes; zoom in and the text underneath is readable. And pixelating or blurring text is weaker than it looks: a blurred line of known font and size can be matched against candidate strings. A solid opaque rectangle has no such weakness.

Cropping is also redaction. If the sensitive part is at the edge, Tools > Crop after drawing a selection removes it entirely, and removed pixels cannot be recovered from the exported file.

Take a cleaner screenshot in the first place

For screenshots, prevention beats cleanup.

  • Press Shift-Command-4, then Space, and click a window. You get that window only, with a transparent surround, and no menu bar, Dock, or desktop.
  • Press Shift-Command-5 for the screenshot toolbar, where Options lets you set a timer so you can dismiss notifications first.
  • Turn on Do Not Disturb before capturing, so banners cannot appear mid-shot.
  • Close other tabs and windows, or use a fresh user account or a guest account for screenshots that will be public.
  • If the menu bar must be in the shot, crop the right-hand end of it where the clock, Wi-Fi name, and account-related icons sit.

Rename the file when you save it. The default name is a timestamp, and it travels with the upload.

Strip the stored metadata

Once the visible content is right, remove what the file stores.

For a single photo, Preview can do the location:

  1. Open the image and press Command-I.
  2. If there is a GPS tab, click it and click Remove Location Info.
  3. Save.

That leaves the camera model, date, and software fields in place, which for many purposes is fine and for an anonymous post is not. The screenshot you exported from Preview in the previous section has no GPS, but it may carry a creation date and the name of the app that wrote it.

For a full strip, or for more than a couple of images, use Manatee’s Clean mode:

  1. Open Manatee and switch to Clean.
  2. Drop the redacted images onto the window, or onto the menu bar icon, or right-click them in Finder and choose Fix with Manatee under Services.
  3. Wait for the job list to finish and collect the cleaned copies beside the originals.

Clean strips GPS and camera EXIF and writes a new file; the original is never modified. It accepts PNG, JPEG, HEIC, WEBP, TIFF, and camera raw files, so phone photos and Mac screenshots can go in the same batch. Everything runs on the Mac with no uploads, which is the right property for images you are about to anonymize. The boundary is the same one as everywhere in this post: Manatee removes metadata, it does not redact pixels. The rectangle in Preview is still your job.

Check the final file

Do this every time, because it takes thirty seconds and catches the mistake where you posted the wrong copy.

  1. Open the file you are about to upload in Preview. Not the original, the one you will post.
  2. Zoom in on every redaction and confirm nothing shows through.
  3. Press Command-I. There should be no GPS tab. Look at the General and EXIF tabs, if present, for a camera model or date you did not intend to share.
  4. Check the filename.
  5. Optionally, run mdls on the file in Terminal and scan for kMDItemLatitude, kMDItemAcquisitionModel, and kMDItemWhereFroms.

The last attribute is an extended attribute, not part of the file, and will not be uploaded by a browser. It is worth knowing it exists if you ever AirDrop or zip the file instead.

What anonymizing an image cannot do

A clean file from a clean account is still a post from you. If the image is of something only you could have photographed, or the screenshot is of a conversation only a few people had, the content identifies you regardless of metadata. Anonymizing the file is necessary, not sufficient.

Uploads also carry their own context: the account, the time of posting, the IP address the platform saw. None of that is in the image, and none of it is fixed by any step above.

For the broader routine, the post at a-privacy-checklist-for-files-you-share-from-a-mac.html covers documents and videos as well as images.

Questions

Is blurring a face good enough?

For faces, a heavy blur or pixelation is usually adequate, since the weakness of blurring mainly applies to text with a known font. For names, account handles, and numbers, use a solid rectangle.

Does converting the image to another format remove the metadata?

Sometimes. A converter may copy EXIF across or drop it, and you will not know which until you check. Use a tool whose purpose is cleaning, then verify with Preview’s Inspector.

Do Mac screenshots contain any location data?

No. A screenshot has no GPS block. It does have a creation date and can carry the name of the app that saved it, and its filename states the time it was taken.

I already posted an image with metadata. What now?

Most platforms strip EXIF from the public copy, so the public exposure may be limited, but the upload itself delivered the original. Delete the post if it matters, and clean the next one before it goes out.